Author Topic: Head cc to small  (Read 947 times)

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Offline Clayton24

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Head cc to small
« on: December 23, 2017, 01:01:32 PM »

Need some opinions or info im getting ready to put se cnc heads on a 2015 limited twin cooled my question is if the combustion chamber ccs is to small to achieve desired compression should i get them changed to the right size or use a thicker head gasket like 0.45 thickness instead off 0.30 an not get the desired quench ! Thanks for all replies

Offline Ohio HD

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Re: Head cc to small
« Reply #1 on: December 23, 2017, 01:04:12 PM »
More details needed to make a good assessment. Motor size, compression goal, plat top pistons or domed, cams used, head cc's measured, where is the piston, flush with the cylinder, down in the cylinder?
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Online PoorUB

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Re: Head cc to small
« Reply #2 on: December 23, 2017, 01:30:47 PM »
Yeah, what he said. Give us all the info and then we can certainly mess with your mind!
I am an adult?? When did that happen, and how do I make it stop?!

Offline Clayton24

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Re: Head cc to small
« Reply #3 on: December 23, 2017, 01:43:07 PM »
Ok sorry  its a 2015 ultra limited 103 cuin with 57h cams with stock flat top pistons ! I have a set of se cnc factory ported heads and the combustion chambers cc at 78cc i wanted to use a 0.30 hg to get the squeeze tighter but ccp is gonna be to high !static is gonna be like 10.79 on big boyz calc and 210 ccp is that to high on a twin cooled ?they are 5 thou in the hole . Tryin to figured which route to go or diffrent cams? Or i can maybe get away with a thicker head gasket ? Or get heads chamber adjusted ! Also i can always get 93 octane ! Thanks for any help greatley appreciated i was thinkn maybe 10.3:1 for this cam !
« Last Edit: December 23, 2017, 01:48:45 PM by Clayton24 »

Offline Ohio HD

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Re: Head cc to small
« Reply #4 on: December 23, 2017, 01:51:14 PM »
In that case, if it were me, I'd use a different set of cams that'll bleed the pressure a little. Or cams that like the higher cylinder pressure. Thicker head gasket works, you just go back to factory squish.
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Offline Clayton24

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Re: Head cc to small
« Reply #5 on: December 23, 2017, 01:58:15 PM »
Im kind of thinkin the same way use the higher compression with a diffrent set of cams ! I realy hate to go to factory quench .

Offline 1FSTRK

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Re: Head cc to small
« Reply #6 on: December 23, 2017, 03:08:13 PM »
how much were the heads shaved?
Did you double check the cc's?

Offline Clayton24

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Re: Head cc to small
« Reply #7 on: December 23, 2017, 03:18:36 PM »
I dont kno how much they were shaved ! But i cced them prob 10 times ! Lol twin cooled heads have a odd shape chamber also (pear shape)

Offline 1FSTRK

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Re: Head cc to small
« Reply #8 on: December 23, 2017, 03:48:45 PM »
 :up:

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Offline Rockout Rocker Products

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Re: Head cc to small
« Reply #9 on: December 23, 2017, 04:06:44 PM »
I had 57s in my wethead Limited, drop in 110 & the CCP was up to 225-230. Put in T-Man 590s to drop the compression... made zero difference.

 The calcs don't = real world every time  :idunno:
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Offline Clayton24

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Re: Head cc to small
« Reply #10 on: December 23, 2017, 04:12:18 PM »
How could that be that it didnt change ? How did u correct it ?sounds like sumthing wasnt right !   :nix:
« Last Edit: December 23, 2017, 04:59:56 PM by Clayton24 »

Offline Ohio HD

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Re: Head cc to small
« Reply #11 on: December 23, 2017, 05:18:13 PM »
Compression calculators in general are close, not absolute though. But when you change intake cam timing in a motor and nothing else, the compression will change. In John's case, there was something else there too. Just not known. One of the cams timing may have been not as advertised. Without degreeing both in the same motor, you just guess at what went wrong.
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Offline Rockout Rocker Products

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Re: Head cc to small
« Reply #12 on: December 23, 2017, 06:22:15 PM »
How could that be that it didnt change ? How did u correct it ?sounds like sumthing wasnt right !   :nix:

 Well, I didn't correct it. I played with the tune a lot, took timing out.... seems to run strong.

 I need to get it to a pro tuner but the only one around here that's recommended is hard to align with... closed weekends and at various other times.

 Maybe I can hook up next week, I'm off work.

Compression calculators in general are close, not absolute though. But when you change intake cam timing in a motor and nothing else, the compression will change. In John's case, there was something else there too. Just not known. One of the cams timing may have been not as advertised. Without degreeing both in the same motor, you just guess at what went wrong.

 As good an explanation as any. Look at the bright side... 'couple hundred thousand miles & the CCP will be right where it should be  :up:
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Offline HD Street Performance

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Re: Head cc to small
« Reply #13 on: December 23, 2017, 07:12:40 PM »
Remember the wet heads start about 81cc.

Offline HD Street Performance

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Re: Head cc to small
« Reply #14 on: December 23, 2017, 07:13:38 PM »
They can be easily opened up and the side benefit of unschrouding the valve

Offline prodrag1320

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Re: Head cc to small
« Reply #15 on: December 24, 2017, 06:18:25 AM »
open the chamber a bit (like said,unshrouding the valves add cc`s) also use some KIBBLEWHITE valves,their dished a lot more than OEM valves & will add cc`s there too

Offline Clayton24

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Re: Head cc to small
« Reply #16 on: December 24, 2017, 11:16:12 AM »
Ok great ! Thanks for the advice ! Very much appreciated !

Offline sfmichael

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Re: Head cc to small
« Reply #17 on: December 24, 2017, 04:44:00 PM »
Ok sorry  its a 2015 ultra limited 103 cuin with 57h cams with stock flat top pistons ! I have a set of se cnc factory ported heads and the combustion chambers cc at 78cc i wanted to use a 0.30 hg to get the squeeze tighter but ccp is gonna be to high !static is gonna be like 10.79 on big boyz calc and 210 ccp is that to high on a twin cooled? they are 5 thou in the hole . Tryin to figured which route to go or diffrent cams? Or i can maybe get away with a thicker head gasket ? Or get heads chamber adjusted ! Also i can always get 93 octane ! Thanks for any help greatley appreciated i was thinkn maybe 10.3:1 for this cam !

absolutely not...just need a good dyno tune when running that high   200+psi / ccp makes for snappy throttle response and great power when tuned correctly
Colorado Springs, CO.

Offline Clayton24

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Re: Head cc to small
« Reply #18 on: December 24, 2017, 07:52:41 PM »
 :up: ok great thats what im after and i am goin for a good dyno tune after engine is back together ! Thanks

Offline Scott P

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Re: Head cc to small
« Reply #19 on: December 26, 2017, 03:55:22 AM »
10.2-10.25 seems to be a great compression for those torque-potent cams.
The off-self heads may need chamber blending to accommodate that ratio, and .040" squish, is not a deal breaker.
Otto Knowbetter sez, "steer clear of chameleons."

Offline Clayton24

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Re: Head cc to small
« Reply #20 on: December 26, 2017, 08:26:52 AM »
 Ok thanks scott i have 2 diffrent thickness head gaskets on the way ! I can use the .036 head gasket and get.040 squish and prob be ok !

Online kd

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Re: Head cc to small
« Reply #21 on: December 26, 2017, 08:50:02 AM »
Clayton, you really should measure your piston deck height before ordering your head gaskets or cutting the heads. If you are trying to get your volume calc proper and set your quench you need to know this info. You may have pistons down in the hole that make up for the cc you "think" you have. Measure first and cut later as they say.
KD

Offline Clayton24

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Re: Head cc to small
« Reply #22 on: December 26, 2017, 09:25:22 AM »
They are .005 in the hole .

Offline Matt C

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Re: Head cc to small
« Reply #23 on: December 26, 2017, 09:54:22 AM »
open the chamber a bit (like said,unshrouding the valves add cc`s) also use some KIBBLEWHITE valves,their dished a lot more than OEM valves & will add cc`s there too
fwiw: If you have to open the chamber up, do it on the spark plug side only. You don't want
to diminish that squish area on the opposite side of the plug (if you can help it)...
Life is like a roll of TP. The closer you get to the end the faster it goes.

Offline Clayton24

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Re: Head cc to small
« Reply #24 on: December 26, 2017, 03:00:02 PM »
Matt c - ok ill keep that in mind !

Offline Matt C

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Re: Head cc to small
« Reply #25 on: December 26, 2017, 05:03:42 PM »
If it were me, I'd get the squish down to the minimum and open up the chamber some. The tight squish will make it
less prone to detonation and make more power (the tuning guy can squeeze the most out of it that way).
Life is like a roll of TP. The closer you get to the end the faster it goes.

Online kd

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Re: Head cc to small
« Reply #26 on: December 26, 2017, 09:01:10 PM »
 :agree: and the added plus of unshrouding the valves as stated before
KD

Offline Clayton24

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Re: Head cc to small
« Reply #27 on: December 27, 2017, 05:35:44 AM »
I like that idea of keepin the squish down too!